This application is based on and claims the priority under 35 U.S.C. xc2xa7119 of German Patent Application 100 65 171.2, filed on Dec. 23, 2000, the entire disclosure of which is incorporated herein by reference.
The invention relates to a method and an apparatus for treating tubular textile goods, and especially tubular knit goods containing a first portion of natural fibers and a second portion of synthetic elastomeric fibers. The treatment may involve, for example, steam treating, heating, relaxing, expanding, and/or heat fixing/setting of the goods.
German Patent Laying Open Publication 198 19 051 A1, and corresponding U.S. Pat. No. 6,016,591 (Strudel et al. ) disclose a method and an apparatus for treating tubular knit goods comprising a first portion of natural fibers and a second portion of synthetic elastomeric fibers. The entire disclosure of U.S. Pat. No. 6,016,591 is incorporated herein by reference, for general information, because the method and apparatus of the present application have similarities with respect to, and represent a further development of, the method and apparatus disclosed in U.S. Pat. No. 6,016,591.
In the known treatment process and apparatus according to U.S. Pat. No. 6,016,591, the tubular knit goods are transported and guided in such a manner that the goods pass along the circular internal spreader or expander arranged in the heat fixing chamber in an upward vertical direction, namely from the bottom to the top of the circular spreader in the heat fixing chamber. While the known method and apparatus according to U.S. Pat. No. 6,016,591 achieve many benefits and advantages in the treatment of the tubular knit goods, a certain disadvantage has also been discovered. Namely, due to the transport of the goods in the vertical upward direction over the circular expander in the heat fixing chamber, this gives rise to a longitudinal tension in the tubular goods, which remains and causes negative influences in the finished product, i.e. the finished treated goods. Particularly, this longitudinal tension is caused by the weight of the tubular goods, the acceleration forces of lifting the tubular goods in the upward transport, the friction of the tubular goods relative to the circumferential surface areas of the circular spreader and the pre-tension force between the fixing rollers of the circular spreader.
German Patent Laying-Open Publication 41 31 636 A1 further discloses a method and an apparatus for carrying out the hot air drying of a spread-out textile web, especially a sensitive or delicate textile web of knit or knitted goods. In the known method and apparatus, before being transported into the hot air drying zone, the knit goods in the form of a flat web are supplied with a leading advance and laid (especially in the form of folds) onto the feed end of an air-permeable carrier belt. Then the goods are transported through the drying zone on this carrier belt. The goods being transported or supplied with a xe2x80x9cleading advancexe2x80x9d means that a quantity of the goods is supplied in excess of or ahead of the demand of the goods being transported away by the carrier belt. The textile web can also be in the form of flat laid-out tubular goods. In order to be able to treat the spread-out flat web of goods using dry air, with an especially low tension of the goods, the known method and apparatus use at least one brush roller extending across the entire width of the flat web to form and lay uniform folds of the flat web onto the feed end of the carrier belt.
In order to subject tubular knit goods made of a first portion of natural fibers and a second portion of synthetic elastomeric fibers to a thermal fixing or heat fixing process, for technological reasons, the knit goods must be supplied to the treatment process in a form or condition other than a flat laid out form and other than a form in which the knit goods are laid out in uniform folds. Namely, such flat or folded forms of the knit goods are not suitable for uniformly carrying out the heat fixing treatment process on knit goods having natural fibers and synthetic elastomeric fibers. While the delivery of a flat web in loose uniform folds on a carrier belt may be suitable for simply heat drying the flat web of material in a low tension manner, it is not suitable for carrying out a heat fixing process, either of tubular goods or of a flat web of goods. For example, the heat fixing process requires the goods to be held and expanded in a controlled configuration with controlled expansion or tension at varying stages of the process.
In view of the above, it is an object of the invention to provide a method and an apparatus for treating tubular textile goods, and especially knit goods with a first proportion of natural fibers and a second proportion of synthetic elastomeric fibers, wherein the transport and guidance of the tubular goods over at least one circular expander or spreader is improved in such a manner so as to reduce the tension forces exerted on and in the goods. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a method for treating tubular textile goods, and especially knit goods with a proportion of natural fibers and a proportion of synthetic elastomeric fibers, in which the textile goods are subjected to a steam treatment process and thereafter a heat fixing process while the goods are in a circular expanded condition and being transported in a vertical direction, i.e. along a vertical axis. According to the invention, the goods are first accumulated to form a goods buffer of a loose excess quantity of the goods upstream of or before the heat fixing treatment, and the transport of the goods during the heat fixing treatment is in a vertically downward direction.
More particularly, a main treatment section of the circular spreader is arranged in the heat fixing chamber of a treatment apparatus while an inlet or feed section of the circular spreader is arranged vertically above the heat fixing chamber. The feed section has a substantially conical configuration, while the main section has a substantially cylindrical configuration which preferably has an adjustable diameter. In this context, the term xe2x80x9csubstantiallyxe2x80x9d means that the configurations of the spreader sections are not truly conical or cylindrical with a truly circular cross-section, but rather the cross-sectional perimeter shape is made up, for example, of a plurality of straight segments, which may be rollers or the like. Thus, the perimeter may be an octagon, decagon, or other polygon rather than a true circle.
In the inventive method, the tubular goods are continuously fed or supplied at a first predetermined transport velocity to the feed section of the circular spreader above the heat fixing chamber whereby the tubular goods temporarily form a goods buffer or excess material reserve on the feed section. The tubular goods are then continuously transported out of the goods buffer on the feed section of the circular spreader at a predetermined second transport velocity, and transported further over the main body section of the circular spreader to be subjected to the heat fixing process in the heat fixing chamber.
The invention may especially include the following features. The tubular goods are first subjected to a steam treatment in a heating chamber, which itself may be per se conventional. The goods are deflected back and forth at least once in the heating chamber and are then delivered continuously at the first transport velocity to the cone-shaped feed section of the circular spreader. The supplied tubular goods form a tubular goods buffer or excess reserve of the tubular goods on the feed section of the circular spreader while temporarily relaxing and possibly shrinking. Next, the tubular goods are continuously transported out of the goods buffer or reserve on the feed section at a second transport velocity that is for example, less than the first transport velocity. Thereby, the tubular goods are transported in a circular expanded condition in a downward vertical direction from the top toward the bottom over the circular spreader while undergoing the heat fixing process. During this downward vertical transport of the tubular goods, the weight of the goods contributes to the downward transport and allows the tension in the goods to be reduced.
As an alternative, the first and second transport velocities can be equal to each other, as long as the first drive and therewith the supply of the tubular goods to the feed section of the circular spreader is operated with a leading advance relative to the second drive that further transports the tubular goods at the second transport velocity from the feed section over the rest of the circular spreader. This leading advance supply of the tubular goods to the feed section of the circular spreader means that an advance reserve quantity of the tubular goods is supplied ahead of or before the transport demand at which the goods are transported away at the second transport velocity. As a simple example, the supply of the goods to the feed section is started a short delay time before starting the transport of the goods away from the feed section, whereby the goods buffer is built up during that short delay time.
The inventive apparatus for carrying out the above method includes a preheating chamber with a steamer device, and downstream thereof a heat or thermal fixing chamber with a circular internal expander or spreader arranged therein. An inlet or feed section of the circular spreader including a spreader head is arranged at the top of or actually above the heat fixing chamber. Various feed rollers and deflection rollers are arranged to transport the goods in a downward vertical direction onto the inlet or feed section and then downwardly over the remainder of the circular spreader through the heat fixing chamber. In this specification, the terms xe2x80x9cupstreamxe2x80x9d and xe2x80x9cdownstreamxe2x80x9d define relative positions with respect to the normal flow or travel direction of the goods along a goods travel path from the beginning to the end of the treatment process through the treatment apparatus.
The inventive method and apparatus achieve the following advantages. The vertically downward transport of the tubular goods, in the circular expanded condition over the circular spreader, from the top to the bottom thereof, beneficially uses the weight and gravitational acceleration of the tubular goods to contribute to the transport. Therefore, the amount of required transport power is reduced, and as a result, the electric motors driving the various drive rollers and the like have a reduced power requirement. Also, as a result of the beneficial gravitational influence, the longitudinal tension of the tubular goods is minimized, which in turn has a positive effect on achieving the desired fixed structure of the knit tubular goods. The formation of a goods buffer in the inlet feed section of the circular spreader gives the goods an opportunity to relax and possibly to shrink in length and width, at least during the time the goods are temporarily stored in this goods buffer or reserve, until the goods are transported out of the buffer at the second transport velocity into the heat fixing chamber.